Flexible display device

ABSTRACT

A flexible display device includes a display panel, at least one inspection part, and a detector. The display panel includes at least one bending portion and a display area. The inspection part is located on the bending portion and bends in a manner similar to the bending portion. The detector applies an inspection signal to the inspection part and receives an output signal from the inspection part. A crack in the inspection part is then determined based on a comparison of the inspection and output signals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application based on pending application Ser. No.14/100,501, filed Dec. 9, 2013, the entire contents of which is herebyincorporated by reference.

Korean Patent Application No. 10-2013-0067902, filed on Jun. 13, 2013,and entitled, “Flexible Display Device,” is incorporated by referenceherein in its entirety.

BACKGROUND 1. Field

One or more embodiments described herein relate to a display device.

2. Description of the Related Art

A flexible display device that includes pixels arranged on a flexiblesubstrate is expected to be very desirable for use in consumer and otherelectronic devices, not only because of its bendable screen but alsobecause such a device could be easily transported.

SUMMARY

A flexible display device may include a display panel including at leastone bending portion and a display area; at least one inspection part onthe bending portion, the inspection part bending with the bendingportion; and a detector to apply an inspection signal to the inspectionpart and to receive an output signal from the inspection part, whereindetector compares the inspection signal and the output signal to detecta crack in the inspection part.

The inspection part may include an inspection pattern on the bendingportion; and a connection wire to electrically connect the inspectionpattern to the detector, wherein the connection wire is to transmit theinspection signal and the output signal between the inspection patternand the detector. The inspection pattern may have a width greater than awidth of the connection wire. The inspection pattern may include asemiconductor material. The semiconductor material may include silicon.

The display panel may include a substrate; a thin film transistor on thesubstrate; a first electrode electrically connected to the thin filmtransistor; an organic light emitting layer on the first electrode toemit light; and a second electrode on the organic light emitting layer.The inspection pattern may include a same material as an active layer ofthe thin film transistor.

The display panel may include a first substrate; a thin film transistoron the first substrate; a first electrode electrically connected to thethin film transistor; a second substrate facing the first basesubstrate; a second electrode on the second substrate; and a liquidcrystal layer between the first and second substrates.

The inspection pattern may include a same material as an active layer ofthe thin film transistor.

The inspection part may have a line shape electrically connected to thedetector to transmit the inspection signal and the output signal. Theinspection line may include molybdenum.

The display area and a bending area included in the bending portion mayoverlap each other. A plurality of inspection parts may be included inthe bending portion. A plurality of bending portions and a plurality ofinspection parts may also be included, wherein each of the bendingportions includes at least one of the inspection parts.

The detector may detect a crack occurring in the inspection part basedon a resistance of the inspection part, the detector determining theresistance of the inspection part based on the inspection signal and theoutput signal.

The display device may include a driving circuit board to drive thedisplay panel, wherein the detector outputs a result signal indicativeof a crack in the inspection part to the driving circuit board, andwherein the driving circuit board controls the display panel based onthe result signal. The driving circuit board may control the displaypanel to be turned off when a crack is detected in the inspection part.

A display device may include a display area; a bent area adjacent thedisplay area; and an inspection part adjacent the bent area, wherein theinspection part and the bent area have substantially a same brittlenessand wherein the inspection part outputs a signal indicative of a crack.The bent area may include a portion of the display area. The portion ofthe display area follows a bend in the bent area.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of ordinary skill in the art bydescribing in detail exemplary embodiments with reference to theattached drawings in which:

FIG. 1 illustrates an embodiment of a flexible display device;

FIG. 2A illustrates a partially enlarged side view of a first area inFIG. 1;

FIG. 2B illustrates views along section lines I-I′ and II-II′ in FIG.2A;

FIG. 3 illustrates another embodiment of a flexible display device;

FIG. 4 illustrates another embodiment of a flexible display device;

FIG. 5 illustrates another embodiment of a flexible display device; and

FIG. 6 illustrates another embodiment of a flexible display device.

DETAILED DESCRIPTION

Example embodiments are described more fully hereinafter with referenceto the accompanying drawings; however, they may be embodied in differentforms and should not be construed as limited to the embodiments setforth herein. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully conveyexemplary implementations to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. It will also be understood thatwhen a layer or element is referred to as being “on” another layer orsubstrate, it can be directly on the other layer or substrate, orintervening layers may also be present. Further, it will be understoodthat when a layer is referred to as being “under” another layer, it canbe directly under, and one or more intervening layers may also bepresent. In addition, it will also be understood that when a layer isreferred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent. Like reference numerals refer to like elements throughout.

FIG. 1 illustrates an embodiment of a flexible display device 500, FIG.2A illustrates a partially enlarged side view showing a first area A1 inFIG. 1, and FIG. 2B is a cross-sectional view taken along lines I-I′ andII-II′ in FIG. 2A.

Referring to FIGS. 1, 2A, and 2B, the flexible display device 500includes a display panel 300, a driving circuit film DF, a drivingcircuit board DP, an inspection part TP, and a detection part SP.

The display panel 300 displays an image in a display area DA thereofusing light. In the present exemplary embodiment, the display panel 300has a flexible property, and thus the display panel 300 may bend toincrease convenience of use. The display panel 300 may be, for example,an organic light emitting display panel or another type of panel.

The display panel 300 includes a display substrate 100 and an oppositesubstrate 200. The opposite substrate 200 faces the display substrate100 while being coupled to the display substrate 100 and preventsmoisture and gas from entering into the display substrate 100. Accordingto another embodiment, the opposite substrate 200 may be omitted in thedisplay panel 300. In this case, the display panel 300 may include asealing layer instead of the opposite substrate 200. The sealing layermay cover the display substrate 100 to prevent the moisture and gas fromentering.

The display substrate 100 includes a base substrate 10, a thin filmtransistor TR, a first electrode E1, a color filter CF, a pixeldefinition layer PDL, an organic light emitting layer EML, and a secondelectrode E2. In the present exemplary embodiment, the display panel 300may be a rear surface light emitting type organic light emitting displaypanel. In this case, the base substrate 10 may be an insulatingsubstrate with light transmittance and flexible properties such asthose, for example, of a plastic substrate.

The thin film transistor TR is disposed on the base substrate 10 and iselectrically connected to the first electrode E1. The thin filmtransistor TR switches a driving signal applied to the first electrodeE1. The thin film transistor TR includes an active pattern AP, a gateelectrode GE, a source electrode SE, and a drain electrode DE. Thesource electrode SE is electrically connected to a driving signal linethat transmits the driving signal and is disposed to overlap with theactive pattern AP. The drain electrode DE is disposed to overlap theactive pattern AP and electrically connect to the first electrode E1.Accordingly, when the thin film transistor TR is turned on, the drivingsignal is applied to the first electrode E1 through the turned-on thinfilm transistor from the driving signal line.

The active pattern AP includes a semiconductor material, which, forexample, may include amorphous silicon or crystalline silicon. Accordingto another embodiment, the active pattern AP may include an oxidesemiconductor material such as IGZO, ZnO, SnO₂, InO₃, Zn₂SnO₄, Ge₂O₃,HfO₂, etc., a compound semiconductor material such as GsAs, GaP, InP,etc., or an organic semiconductor material, such as pentacene.

A gate insulating layer L1 is disposed between the gate electrode GE andthe active pattern AP, and an inter-insulating layer L2 covers the gateelectrode GE to insulate the gate electrode GE from the source and drainelectrodes SE and DE. An organic layer L3 covers the thin filmtransistor TR and includes a contact hole CH formed therethrough. Thefirst electrode E1 is electrically connected to the drain electrode DEthrough the contact hole CH.

The first electrode E1 is disposed on the organic layer L3 and serves asan anode electrode. As described above, when the display panel 300 isthe rear surface light emitting type organic light emitting displaypanel, the first electrode E1 may be formed of a transparent conductivelayer, e.g., indium tin oxide (ITO), indium zinc oxide (IZO), etc.

The pixel definition layer PDL is disposed on the organic layer L3, andthe first electrode E1 is partially opened in an area corresponding tothe first electrode E1. Thus, the organic light emitting layer EML isdisposed on the first electrode E1 through the opened portion of thepixel definition layer PDL.

The organic light emitting layer EML is disposed on the first electrodeE1, and the second electrode E2 that serves as a cathode electrode isdisposed on the organic light emitting layer EML. Therefore, holesprovided through the first electrode E1 and electrons provided throughthe second electrode E2 are recombined with each other in the organiclight emitting layer EML, so that the organic light emitting layer EMLemits light.

In the present exemplary embodiment, the light emitted from the organiclight emitting layer EML may be white light. In this case, the organiclight emitting layer EML may have a single-layer structure and isdisposed in pixel and non-pixel areas. In addition, a hole injectionlayer and a hole transport layer may be sequentially disposed betweenthe first electrode E1 and the organic light emitting layer EML. Also,an electron transport layer and an electron injection layer may besequentially disposed between the organic light emitting layer EML andthe second electrode E2.

The color filter CF is disposed on the base substrate 10 and filters thelight emitted from the organic light layer EML. When the organic lightemitting layer EML emits white light, the color filter CF filters thewhite light to output color light.

The second electrode E2 is disposed on the organic light emitting layerEML. In the present exemplary embodiment, the second electrode E2 mayinclude a conductive material (e.g., a metal material) to reflect thelight. The light emitted from the organic light emitting layer EML isreflected by the second electrode E2 and travels toward the color filterCF.

A protective layer 150 may be interposed between the display substrate100 and the opposite substrate 200. The protective layer 150 mayinclude, for example, a polymer material such as a polyimide resin, toprevent moisture and gas from entering into the display substrate 100.

The display panel 300 includes a bending portion BP configured toinclude a first bending area BA1 and a second bending area BA2 due tothe flexible property thereof. In the present exemplary embodiment,since an edge of the display panel 300 is bent, the display panel 300includes the bending portion BP and the first and second bending areasBA1 and BA2 overlap the display area DA. Thus, the image may bedisplayed in a portion of the bending portion BP. According to anotherembodiment, the bending portion BP may be disposed outside the displayarea DA and the image is not displayed in the bending portion BP.

The driving circuit board DP generates various signals to drive thedisplay panel 300. For example, the driving circuit board DP may includea timing controller T-CON to generate driving signals to control theimage displayed in the display panel 300.

The driving circuit film DF has a flexible property as a flexibleprinted circuit film and electrically connects a pad part PP of thedisplay substrate 100 to the driving circuit board DP. Thus, the drivingsignals are applied to a driving chip DC bonded to the pad part PPthrough the driving circuit film DF.

In the present exemplary embodiment, the driving chip DC converts thedriving signals into gate signals and data signals, and the gate anddata signals are applied to gate lines and data lines, respectively,disposed on the display substrate 100. Therefore, pixels PXLelectrically connected to the data lines and the gate lines are driven,so that the image is displayed in the display area DA.

The inspection part TP is disposed outside the display area DA and maybe disposed, for example, on the bending portion BP. The inspection partTP may therefore be bent with the bending portion BP. In one embodiment,the inspection part TP includes an inspection pattern AP_1, a firstconnection wire LW1, and a second connection wire LW2. The inspectionpattern AP_1 may have a width greater than that of the first and secondconnection wires LW1 and LW2. The first connection wire LW1 connects oneend of the inspection pattern AP_1 to the detection part SP and thesecond connection wire LW2 connects another end of the inspectionpattern AP_1 to the detection part SP.

In the present exemplary embodiment, each of the inspection patternAP_1, the first connection wire LW1, and the second connection wire LW2may include a material having a high brittleness as compared to thesignal lines of the display panel 300, e.g., gate and data lines. Forinstance, when the signal lines of the display panel 300 includealuminum, the inspection pattern AP_1 may include a semiconductormaterial (e.g., silicon) and the first and second connection lines LW1and LW2 may include molybdenum. Accordingly, cracks may easily occur inthe inspection part TP to a greater degree than the signal lines of thedisplay panel 300.

When the inspection pattern AP_1 includes silicon, the inspectionpattern AP_1 may be formed through the same process as the activepattern AP. Thus, the inspection pattern AP_1 and the active pattern APmay be formed from the same material. The inspection pattern AP_1 andthe active pattern AP may be disposed between the base substrate 10 andthe gate insulating layer L1.

The detection part SP is electrically connected to the inspectionpattern TP by the first and second connection wires LW1 and LW2. Thedetection part SP is mounted on the driving circuit substrate DP, andthe detection part SP and the inspection pattern AP_1 are electricallyconnected to each other by the first and second connection wires LW1 andLW2 extending along the pad part PP and the driving circuit film DF.

The detection part SP applies an inspection signal to the inspectionpattern AP_1 through the first connection wire LW1 and receives anoutput signal output from the inspection pattern AP_1 through the secondconnection wire LW2, which corresponds to the inspection signal. Inaddition, the detection part SP compares the inspection signal and theoutput signal to detect the cracks in the inspection pattern AP_1. Forinstance, the detecting part SP includes a logic circuit that compares avoltage value of the input signal and a voltage value of the outputsignal to measure a resistance of the inspection pattern AP_1. In thiscase, the detection part SP detects the cracks of the inspection patternAP_1 on the basis of a variation in resistance of the inspection patternAP_1.

In the present exemplary embodiment, the detection part SP is mounted onthe driving circuit board DP. However, in other embodiments, the logiccircuit of the detecting part may be built into the driving chip DC, andthus the driving chip DC may serves as the detection part SP.

The detection part SP is electrically connected to the timing controllerT-CON by a third connection wire LW3 and applies a result signal relatedto the occurrence of the cracks in the inspection pattern AP_1 to thetiming controller T_CON through the third connection wire LW3.Therefore, the timing controller T_CON controls the driving of thedisplay panel 300 in response to the result signal. For instance, whenthe cracks occur in the inspection pattern AP_1, the timing controllerT_CON turns off the display panel 300 on the basis of the result signal.

According to the configurations of the inspection part and the detectionpart TP, a possibility of cracks occurring in the bending portion BP maybe predicted on the basis of whether cracks occur in the inspection partTP. In addition, since the timing controller T_CON receives the resultsignal from the detection part SP, the flexible display device 500 maycontrol the driving of the display panel 300.

According to one application, when the flexible display device 500 ismanufactured, potential defects in operation of the display panel 300,caused by the cracks in the bending portion BP, may be easily detectedusing the detection part SP and the inspection part TP. In addition,because a user perceives turn-off of the display panel 300, generated bythe operations of the inspection part TP and the detection part SP, aspotential defects in operation of the display panel 300, the user isprevented from feeling inconvenient while the user uses the flexibledisplay device 500.

FIG. 3 is a cross-sectional view of another embodiment of a flexibledisplay device 501 which includes a display panel 301. The display panel301 may be a liquid crystal display panel having a flexible property.The display panel 301 includes a display substrate 101, an oppositesubstrate 201, and a liquid crystal layer LC.

The display substrate 101 includes a first base substrate 10, a thinfilm transistor TR disposed on the first base substrate 10, a firstelectrode E1 electrically connected to the thin film transistor TR, anda color filter CF. In addition, the opposite substrate 201 includes asecond base substrate 210 facing the first base substrate 10 and asecond electrode E2 disposed on the second base substrate 210.

The liquid crystal layer LC is disposed between the display substrate101 and the opposite substrate 210. A backlight unit may be disposedunder the display panel 301 to supply the light to the display panel301.

As described with reference to FIG. 1, the display panel 301 of theflexible display device 501 includes a bending portion and an inspectionportion TP disposed on the bending portion. In addition, the flexibledisplay device 501 includes a driving circuit film, a driving circuitboard, and a detection part similar to those shown in FIG. 1.Accordingly, the detection part may detect the cracks in the inspectionspart TP and controls the display panel 301 to be turned off on the basisof the output signal relating to the cracks in the inspection part TP.

FIG. 4 illustrates another embodiment of a flexible display device 502which includes a display panel 300. The display panel 300 includes abending portion BP configured to include first and second bending areasBA1 and BA2.

The inspection part TP described with reference to FIG. 1 is disposed inthe bending portion BP in a plural number. For instance, two inspectionparts TP may be provided to the bending portion BP, one inspection partTP of the two inspection parts TP is disposed at one end of the bendingportion BP, and the other inspection part TP of the two inspection partsTP is disposed at the other end of the bending portion BP.

The two inspection parts TP are disposed at different positions fromeach other. Each of the inspection parts TP may have a similarconfiguration to that of the inspection part TP described with referenceto FIG. 1. More specifically, each of the inspection parts TP mayinclude an inspection pattern AP_1, a first connection wire LW1, and asecond connection wire LW2, which are disposed in the first and secondbending areas BA1 and BA2. The first connection wire LW1 and the secondconnection wire LW2 electrically connect the inspection pattern AP_1 tothe detection part SP after detouring the display area DA.

FIG. 5 illustrates another embodiment of a flexible display device 503which includes a display panel 302. The display panel 302 includes adisplay substrate 102 and an opposite substrate 202. In the presentexemplary embodiment, the display panel 302 includes a plurality ofbending portions. For instance, the display panel 302 includes a firstbending portion BP1 and a second bending portion BP2, and the first andsecond bending portions BP1 and BP2 are disposed at both edges of thedisplay panel 302.

In addition, two inspection parts TP are provided to the display panel302 and disposed to correspond to the first and second bending portionsBP1 and BP2 in a one-to-one correspondence. The two inspection parts TPare disposed at different positions from each other. Each of theinspection parts TP may have a similar configuration to that of theinspection part TP described with reference to FIG. 1. Morespecifically, each of the inspection parts TP may include an inspectionpattern AP_1, a first connection wire LW1, and a second connection wireLW2. The first connection wire LW1 and the second connection wire LW2may electrically connect the inspection pattern AP_1 to the detectionpart SP after traversing around the display area DA.

FIG. 6 illustrates another embodiment of a flexible display device 504including an inspection part TP′ having a line shape electricallyconnected to the detection part SP. In this case, the inspection partTP′ may include a metal material (e.g., molybdenum), with a brittlenesshigher than that of aluminum used to form the signal lines of thedisplay panel.

In the flexible display device 504 shown in FIG. 6, although theinspection part TP′ has the line shape without including the inspectionpattern AP_1 (refer to FIG. 1), cracks occurring in the inspection partTP′ may be easily detected by the inspection part TP′ and the detectionpart SP, because the inspection part TP′ includes the metal material inwhich the cracks are easily transmitted.

By way of summation and review, a malfunction in a flexible displaydevice may occur as a result of excessive stress applied to its signallines and conductive patterns. Such a malfunction may include theformation of cracks in the signal lines and conductive patterns. Thesecracks might be found during an inspection process, but only after thecracks have become significantly long so as to make then noticeable.Cracks of smaller or minute length may not be detected, but still maycause defects and/or malfunctions that will only get worse over time.

In contrast, embodiments provide a flexible display device including adisplay panel, an inspection part, and a detection part. The displaypanel includes a bending portion and displays an image. The inspectionpart is disposed on the bending portion and bent together with thebending portion. The detection part applies an inspection signal to theinspection part and receives an output signal output from the inspectionpart, and the detection part compares the inspection part and the outputsignal to detect a crack of the inspection part.

According to the above, the crack occurring in the inspection partdisposed in the bending portion of the display panel may be detected bythe detection part. Since the inspection part is bent together with thedisplay panel, a possibility that the cracks occur in the display panelmay be predicted on the basis of the cracks in the inspection part

Thus, when the crack occurring in the inspection part is detected by thedetection part, the result signal related to the occurrence of the crackin the inspection part is applied to the driving circuit substrate, andthe driving circuit substrate controls the display panel to be turnedoff on the basis of the result signal.

Therefore, when the flexible display device is manufactured, potentialdefects in operation of the display panel, which are caused by the crackin the bending portion, may be easily detected using the detection partand the inspection part. In addition, since a user perceives theturn-off of the display panel, which is generated by the operations ofthe inspection part and the detection part as the potential defects inoperation of the display panel, the user is prevented from feelinginconvenient while the user uses the flexible display device.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

What is claimed is:
 1. A flexible display device comprising: a displaypanel including a bending portion configured to display an image; aninspection pattern on the bending portion; a driving circuit boarddriving the display panel; a detector disposed on the driving circuitboard; and a connection wire electrically connecting the inspectionpattern and the detector, wherein the detector is to apply an inspectionsignal to the inspection pattern and to receive an output signal fromthe inspection pattern, wherein the detector is to compare theinspection signal and the output signal to detect a crack in theinspection pattern.
 2. The flexible display device as claimed in claim1, wherein the connection wire comprises: a first connection wireconnected to one end of the inspection pattern; and a second connectionwire connected to another end of the inspection pattern.
 3. The flexibledisplay device as claimed in claim 2, wherein the detector applies theinspection signal to the inspection pattern through the first connectionwire, and receives the output signal from the inspection pattern throughthe second connection wire.
 4. The flexible display device as claimed inclaim 2, further comprising: a timing controller disposed on the circuitboard; and a third connection wire electrically connecting the detectorand the timing controller.
 5. The flexible display device as claimed inclaim 1, wherein the detector detects a crack occurring in theinspection pattern based on a resistance of the inspection pattern, thedetector determining the resistance of the inspection pattern based onthe inspection signal and the output signal.
 6. The flexible displaydevice as claimed in claim 5, wherein the detector outputs a resultsignal indicative of the crack in the inspection pattern to the drivingcircuit board, and wherein the driving circuit board controls thedisplay panel based on the result signal.
 7. The flexible display deviceas claimed in claim 6, wherein the driving circuit board controls thedisplay panel to be turned off when the crack is detected in theinspection pattern.
 8. The flexible display device as claimed in claim1, wherein the detector comprises a logic circuit that compares avoltage value of the input signal and a voltage value of the outputsignal to measure a resistance of the inspection pattern.
 9. Theflexible display device as claimed in claim 1, wherein the display panelcomprises: a substrate; and a signal line disposed on the substrate, thesignal line includes gate line and data line, and wherein the inspectionpattern is more brittle comparing to the signal line.
 10. The flexibledisplay device as claimed in claim 1, wherein the inspection patterncomprises a semiconductor material.
 11. The flexible display device asclaimed in claim 10, wherein the display panel comprises: a substrate; athin film transistor on the substrate; a first electrode electricallyconnected to the thin film transistor; an organic light emitting layeron the first electrode emitting light; and a second electrode on theorganic light emitting layer.
 12. The flexible display device as claimedin claim 11, wherein the inspection pattern comprises a same material asan active layer of the thin film transistor.
 13. The flexible displaydevice as claimed in claim 10, wherein the display panel comprises: afirst substrate; a thin film transistor on the first substrate; a firstelectrode electrically connected to the thin film transistor; a secondsubstrate facing the first substrate; a second electrode on the secondsubstrate; and a liquid crystal layer between the first and secondsubstrates.
 14. The flexible display device as claimed in claim 13,wherein the inspection pattern comprises a same material as an activelayer of the thin film transistor.
 15. A display device, comprising: adisplay panel including a bending portion configured to display animage; an inspection pattern on the bending portion; a driving circuitboard driving the display panel; a detector is disposed on the drivingcircuit board; and a connection wire electrically connecting theinspection pattern and the detector, wherein the inspection pattern andthe bending portion have substantially a same brittleness, and whereinthe inspection pattern outputs a signal indicative of a crack in theinspection pattern.